Hi all, I am running my protein sample using mass spectrometry.. I noticed that there are sodium adducts in my protein sample. I want to reduce the amount of sodium ions in my sample. I was told that glasswares tend to have a lot of sodium ions. Would autoclaving degrade sodium ions so that if my samples caught sodium ions from glasswares that I used, would they diminish once I autoclave them?
Thanks!
No, please do not use your autoclave. Sodium ions are everywhere. To reduce them, you must use good laboratory practices and keep all of the glassware used with your HPLC and MS system very clean and washed according to strict cleaning methods which do not use any dishwashers, autoclaves or soap detergents.
I have attached an article to this post which will provide you with an excellent overview of how to reduce contamination in general. Lots of good advice contained within.
As Bill said above, autoclaving won't do anything for you and may even make things worse. Sodium ions come from the glassware and even the fused silica tubing used in many HPLC systems. Keep in mind sodium silicate, a major component of glass, is slightly soluble in water, autoclaving will dissolve more sodium silicate from the glass especially when the solution is heated. To minimize the sodium adducts use acidic mobile phases, use plastic solvent reservoirs (that don't contain plasticizers like Teflon) eliminate fused silica tubing (use peek if possible).
Keep in mind that most purchased HPLC grade water comes packaged in glass bottles which means it will be saturated with sodium silicate. To get water that is free of sodium silicate you would have to collect it from a high quality water purification system right into a plastic solvent reservoir.
Your sample could also contain appreciable amounts of sodium ions. Dialyze or purify your sample using an absorption technique (such as SPE) use only ammonium ion salts in protein processing steps. For tryptic digests use 100mM n-ethylmorpholine as the buffer which gives pH 8. Use plastic (not glass) syringes to load your sample into an injector loop.
As Bill and Bruce explained, the answer is very clear.
I just want to add a comment that sometimes sodium adduct actually can enhance your MS response and help for identification, like intact protein and metabolites.
So how to deal with sodium adduct really depends on your sample characters.